Arrange tofu in a single layer on a plate between several layers of paper towels. Top with a heavy skillet; let stand for 5 minutes. In a bowl, mix mayonnaise, ketchup and chopped pickles; cover. In a separate bowl, mix coriander, pepper, garlic powder, salt and sugar. Discard towels around tofu. Brush tofu with Worcestershire; sprinkle all over with spice mixture.
Warm oil in a large nonstick skillet over medium-high heat. Cook tofu, turning once, until browned, 6 to 8 minutes. Transfer to a plate. Add sauerkraut and jalapeño to skillet; sauté until heated through, about 2 minutes. Transfer to a bowl, cover and keep warm. Wipe out skillet.
Spread butter on 1 side of each bread slice; set it buttered-side down on a work surface. Spread 1 Tbsp. mayonnaise mixture on 4 slices; top with cheese, tofu and pickles, if desired. Mound sauerkraut on top; drizzle with remaining mayonnaise mixture. Close sandwiches. Warm 2 skillets over medium heat. Cook sandwiches, turning once, until bread is crisp and cheese has melted, about 5 minutes. Cut in half and serve right away.